AAEM species, such as inorganic and organic states, are distributed in the pyrolysis biochar, which affect the reactivity of biochar. The speciation of AAEM species in biochar was determined by chemical analysis fractionation and ICP-AES. The effect of AAEM species on the reactivity of biochar was analyzed by the thermal gravimetric analysis. The results show that the Na and K elements are mainly water-soluble, while the Ca and Mg elements are mainly in the insoluble state. At 370 ℃, NH₄Ac-soluble AAEM species are responsible for the middle and late stage in the reaction. Washed by H₂O, NH₄Ac and HCl successively, the reactivity of biochar decreases. When the carbon conversion rate is relatively small, the water-soluble AAEM species play an important role in promoting the reactivity of biochar. When the carbon conversion rate is higher than a certain value, the reactivity of original biochar is lower than that of the H₂O-washed biochar. The catalytic effect of NH₄Ac-soluble AAEM species on the reactivity of biochar is relatively stable, and the effect of HCl-soluble AAEM species is the most.